Seaweed based biostimulants for improving plant growth has been well known for a long time. Seaweed extracts and suspensions have achieved a broader use and market than seaweed and seaweed meal. The seaweed species used are mostly temperate, which grow in colder waters. Several reviews have covered the use of seaweed extracts for Agriculture (Khan et al. J. Plant Growth Regul. (2009) 28:386-399; Craigie et al—J Appl Phycol (2011) 23:371-393).
Biostimulants are currently mainly made from brown seaweeds, although the species varies between countries. Some are made by alkaline extraction of the seaweed and anything that does not dissolve is removed by filtration (e.g. Maxicrop and Seasol). Others are suspensions of very fine particles of seaweed (Goëmill and Kelpak 66). For Goëmill, the seaweed (Ascophyllum) is rinsed, frozen at −25° C., crushed into very fine particles and homogenized; the result is a creamy product with particles of 6-10 micrometers; everything from the seaweed is in the product. Other chemicals may be added to improve the product for particular applications. Kelpak first appeared in 1983 and the originators say it is made from Ecklonia maxima by a cell-burst procedure that does not involve the use of heat, chemicals or dehydration. Fresh plants are harvested by cutting from the rocks at the stipe (stalk) and then they are progressively reduced in particle size using wet milling equipment. These small particles are finally passed under extremely high pressure into a low-pressure chamber so that they shear and disintegrate, giving a liquid concentrate. (McHugh, D. 2003. A guide to the seaweed industry Page 92).
U.S. Pat. No. 6,893,479 and its equivalent outlines a process whereby fresh red seaweed Kappaphycus alvarezii can be used to produce a biofertilizer by using the juice part of the red seaweed as a growth stimulant. The solids part of the seaweed is dried and converted into carrageenan. This patent does not envisage the use of the solid residue (carrageenan) as a biostimulant.
US 2010/173779 A1, US2011/0099898 A1 and its equivalents outlines a process where the oligo carrageenan polymers of around 20 sulphated galactose units obtained from carrageenan derived from seaweed species have been shown to have growth promoting effects and defense against pathogens.